The Mothae mine, located in the Maluti Mountains of Lesotho is known to produce large, high-value diamonds which command the second highest dollar per carat for kimberlite diamonds worldwide. The company relies on TOMRA’s XRT sorting technology and digital solutions – the TOMRA Insight platform and TOMRA ACT user interface – to recover large unbroken diamonds from the mine with high sorting efficiency and high throughput, while benefiting from lower operational costs.
Global diamond producer Lucapa Diamonds owns 70% of Mothae Diamonds, an open-pit mine located in the diamond-rich Maluti Mountains of Lesotho, which started commercial operation in 2019 following the commissioning of its kimberlite processing plant. The mine is known to produce large, high-quality diamonds, and has had significant gem-quality recoveries including a 215 carat D-colour Type IIa, a 204 carat Type IIa, and rare pink, blue and yellow fancy-colored diamonds.
When planning the recovery plant, Mothae turned to TOMRA Mining for a solution: “We wanted to recover large diamonds at the highest sorting efficiency with the highest throughput, and TOMRA met Mothae’s requirements with its modern and innovative technology,” says Macobone Semelani, Recovery Superintendent.
The recovery plant operates two TOMRA COM Tertiary XRT 1200 sorters: one for fines from 10mm to 20mm, and the other for coarse materials from 20 mm to 45 mm. The ore extracted from the mine is treated through primary crushing, scrubbing and screening, then transferred to the recovery area: “That’s where the TOMRA sorters separate diamonds from the ore,” explains Kothalo Matoli, Recovery Mechanician. “TOMRA sorters are the best of the best. With them, we are able to recover large diamonds prior to secondary and tertiary crushing, hugely reducing the risk of breakages, and our throughput is high, with 98% efficiency guaranteed.” Semelani adds: “We now benefit from the increased tonnage throughput following the increase in belt speed from 2.7 m/s to 3m/s, and we have the lowest production cost compared to the conventional and legacy methods.”
The two TOMRA XRT sorters at Mothae are connected to the TOMRA Insight cloud-based data platform that turns the machines into connected devices that generate valuable data and puts operators in control of the sorting process. They also feature the TOMRA ACT user interface, which facilitates the optimization of the workflow and improves productivity.
Semelani explains: “As a relatively small and low-grade mine, we are always investigating the latest technologies. With our sorters operating 24 hours a day, seven days a week, we were looking to maintain and upgrade our sorters to the latest compatible software and hardware. We wanted a portal that is user-friendly so our operators can easily interact with the sorters. TOMRA ACT now provides clear visualisation of events and alarms, and captures the images of the belt occupancy. It also shows the ejection activity.”
“TOMRA Insight has changed the way we are running our production because we can monitor our sorters remotely and we can access reports from both machines in one interface,” says Matoli. “All the alarms and events are logged on the sorter in real time, enabling me to troubleshoot very fast. My troubleshooting skill has improved a lot.”
TOMRA Insight also stores and backs up all the data generated by the sorters so that the operator can analyse the complete history of each machine. “Digital data is crucial. TOMRA Insight has exceeded my expectations because I can access data whenever I want, wherever I am. I have at my fingertips the learnings about my sorters, their operation and maintenance. We can see the belt occupancy and our ejection rate, and understand if a machine is over-ejecting due to foreign objects in the material, for example. The utilisation of the sorters has improved, enabling us to process more tons and recover more carats.”
“I can monitor the sorters’ operational and health status from the office or offsite. TOMRA Insight captures and compiles all the data in one interface, generating reports and data analyses, improving data management and analytics for better decision-making. With TOMRA Insight, I see advanced sorting solutions in the future and automated recovery plants,” adds Semelani.
Semelani is also very impressed with the support received from TOMRA: “The TOMRA team has been very supportive since day one and their service is outstanding.” Matoli agrees: “They are always available whenever we need them. They help us remotely and if we need somebody on site, they are always ready to come.”
